As drugs for treating hypertension, many drugs are being used, such as calcium antagonists, renin-angiotensin system inhibitors (angiotensin-converting-enzyme (ACE) inhibitors and angiotensin receptor antagonists), diuretics, sympatholytic agents (α-blockers, β-blockers, and αβ-blockers), vasodilators, and the like.
Despite the presence of these many hypotensive drugs, in the actual clinical practice the proportion of patients who have attained the target level of blood pressure is as low as about 40% (NPL 1). Above all, with high-risk patients having backgrounds such as advanced age, diabetes, renal disorder, long period of suffering from hypertension, and the like, the proportion of patients who attain the target blood pressure level is still lower (NPL 2). Therefore, in the recent guidelines for hypertension, a concomitant treatment with two or more kinds of drugs is recommended and actually the number of cases of concomitant treatment is increasing (NPL 3). There are more than a few cases where three or more kinds of drugs are used concomitantly in order to attain the target blood pressure level (NPL 4). However, in the concomitant use of existing hypotensive drugs, it is known that no additive hypotensive effect is obtained in combined use of, for example, an ACE inhibitor and β-blocker, and in a concomitant use of an ACE inhibitor and angiotensin receptor antagonist (NPL5 and 6). In addition, there is a possibility that adverse drug reactions of each drug become pronounced by the concomitant use, such as bradycardia observed in the combined use of diltiazem, a calcium antagonist and a β-blocker, and metabolic disorders including elevated uric acid level, high blood sugar level, lipid abnormality, and the like seen in the concomitant use of a diuretic and β-blocker (NPL 7 and 8). Therefore, in order to open up treatment options, a drug is desired, which has less adverse drug reactions and has a mechanism different from that of the existing hypotensive drugs.
It has become clear that 2-(3-cyano-4-isobutyloxyphenyl)-4-methyl-5-thiazolecarboxylic acid or its medicinally acceptable salt, which has a uric acid lowering effect, shows a hypotensive effect by a mechanism different from the existing hypotensive drugs (PTL 1).